1. Field of the Invention
This invention relates to a method and apparatus for manufacturing miniature harps utilized to secure slices of vertebrate brain to the bottom of a recording chamber during electrophysiological recordings.
2. Description of the Related Art
Please refer to FIG. 1 xe2x80x9cPrior Artxe2x80x9d for the following explanation of the related art. Electrophysiological recording from vertebrate brain neurons and glial cells in semi-intact brain slice preparations is a well-established technique in modern neuroscience. Slices 50 having a thickness t of approximately 0.1 mm, and ranging from roughly 1 to 3 mm in diameter d, are cut (using a razor blade mounted on a xe2x80x9cvibratomexe2x80x9d) from living brain tissue that has been acutely dissected from a vertebrate animal. Such a slice 50 is placed in a recording chamber under a compound microscope so that the neurons and glia, as well as the tip of the electrode, can be seen during the course of electrophysiological recording. In order to keep the neurons and glia in the tissue slice alive, and to allow for the introduction of pharmacological agents, oxygenated saline solution continuously flows through the chamber.
Unless the slice of brain tissue is secured in some fashion to the bottom of the recording chamber, the flow of saline would cause the slice to drift and otherwise move in the chamber. This makes it impossible to obtain successful electrophysiological recordings from neurons or glia in the slice. However, the use of miniature harps to secure the brain slice to the bottom of the recording chamber is well known in the art.
The harp 100 is a xe2x80x9cUxe2x80x9d-shaped piece of flattened metal wire 10 that has been strung between the arms 20a,b parallel to the base of the xe2x80x9cUxe2x80x9d 30 with the separated strands 40 of woven synthetic fiber dental floss. The strands 40 are strung at a spacing s of roughly 1 mm. The xe2x80x9cUxe2x80x9d 10 is of a width W and a length L that when laid flat, a brain slice 50 such as described above can be completely surrounded on three sides by the xe2x80x9cUxe2x80x9d. In other words, the brain slice is inside the xe2x80x9cUxe2x80x9d. When the harp is laid atop the brain slice, the strands of dental floss transfer some of the weight of the metal xe2x80x9cUxe2x80x9d onto the slice, thereby securing it to the bottom of the recording chamber. Because the strands of dental floss have some flexibility, not all of the weight of the xe2x80x9cUxe2x80x9d is borne by the brain slicexe2x80x94some of it is borne by the bottom of the recording chamber.
Such harps are constructed one-by-one by hand, in a tedious and painstaking procedure as follows. A piece of wire, approximately 0.2 mm in diameter, made from a heavy and relatively non-reactive metal such as platinum is cut to a length of approximately 30 mm. This piece of wire is then bent into a squared xe2x80x9cUxe2x80x9d shape, with each arm of the xe2x80x9cUxe2x80x9d being approximately 10 mm in length. Then, the xe2x80x9cUxe2x80x9d is hammered flat, so that one flattened side of the wire will touch the bottom of the recording chamber when the completed harp is laid therein, and the other flattened side faces directly upwards.
The flattened metal xe2x80x9cUxe2x80x9d is then pushed into a wide horizontal platform fashioned from modeling clay, so that the xe2x80x9cUxe2x80x9d is lying down in the clay in the same configuration as if it were lying down in the recording chamber. Separated strands of dental floss are then strung across the xe2x80x9cUxe2x80x9d, parallel to the open edge and with a roughly 1 mm spacing between each strand. The ends of each strand are temporarily secured by pressing them into the modeling clay that surrounds the xe2x80x9cUxe2x80x9d. Once all of the necessary number of strands (usually 5-10) have been temporarily secured, a tiny droplet of quick-drying xe2x80x9csupergluexe2x80x9d-type cement is applied to each of the two points of contact between each strand of dental floss and the metal xe2x80x9cUxe2x80x9d. Once the glue has dried, the strands are severed just distal to their glued contacts with the metal xe2x80x9cUxe2x80x9d, and the resulting completed electrophysiology harp can be removed from the modeling clay platform and put to its intended use.
The aspect of this prior-art method of manufacture of electrophysiology harps that is most tedious and potentially frustrating to the electrophysiologist is the stringing of the separated dental floss strands across the arms of the xe2x80x9cUxe2x80x9d, and temporarily securing them by pressing them into the modeling clay. This aspect of the procedure is by far the most time-consuming. The separated strands, because they are so thin, must be manipulated with small forceps. Frequently, as one strand is being temporarily secured by pressing into the clay, other, already temporarily secured, strands are being displaced. Indeed, it is well known by those of skill in the electrophysiological arts that this step of the method can result in the use of unfortunate language by the investigator. Also, this method is not easily adapted to the manufacture of more than one harp at a time. In addition, this method results in harps that exhibit substantially uneven spacing and deviation from parallel to the base of the xe2x80x9cUxe2x80x9d.
It is clear, then, that a novel method for the manufacture of electrophysiology harps that alleviates both the inconvenience of the temporary strand securing step of the prior art method, the inability to simultaneously manufacture a plurality of harps, and the uneven spacing and deviation from parallel would be well-appreciated by electrophysiologists.
It is an object of this invention to provide an apparatus and method for manufacturing electrophysiology harps that is faster and/or more convenient than the apparatus and method available in the prior art.
It is an additional object of this invention to provide an apparatus and method for manufacturing electrophysiology harps that allows for the manufacture of more than one harp substantially simultaneously.
It is a further object of this invention to provide an apparatus and method for manufacturing electrophysiology harps that allows for the manufacture of harps that exhibit substantially evenly spaced and substantially parallel strands.
It is further still an object of this invention to provide an electrophysiology harp that exhibits substantially evenly spaced and substantially parallel strands.
Consistent with the present invention is a jig for the manufacture of electrophysiology harps containing a top surface upon which may be placed one or more xe2x80x9cUxe2x80x9ds and two arrays of strand-securing notches, wherein the arrays of notches are situated one on each of two opposing edges of the top surface of the jig. Also consistent with the present invention is a method for the manufacture of electrophysiology harps exhibiting the steps of placing xe2x80x9cUxe2x80x9ds on the top surface of such a jig, stringing one or more strands across the xe2x80x9cUxe2x80x9ds such that points of contact form between the strands and the xe2x80x9cUxe2x80x9ds, securing the strands in the notches, cementing the points of contact, and severing the strands just distal to the points of contact. Additionally consistent with the present invention is an electrophysiology harp with strands that are substantially parallel to one another and/or equidistant from one another.